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THE DUGONG                                     337

form; there appears to be but a single species, though more than
one name lias been ghvii to supposed distinct species. As already
mentioned, it differs from the Manatee in the possession of a
"Wh.tle-like tail ; the nostrils, too, are more upon, the upper surface
of the liead^ and, there are no nails upon the flipper. The peculiar
eleft lip of the Manatee is not so well developed in the Diigong,
but there are traces of It ; and in the foetus the likeness to the
Manatee in this resp^t is very striking. It would thus appear
that ffdlicore is a stage in advance upon JtfanatiLS ; that the
remarkable mechanism of the lip of the latter has been possessed,,
but has been lost, by thr* Ihicjong. The skull of the Dugong is
distinguished by the stunt |i>v maxillary bones, which bear a tusk
in the male. In the female the tooth is there, but is lodged within
the bone. This incisor has a milk forerunner. The back teetli
of the Dugong (there are no canines) are few in number (four or
live, even six), thus showing a gradual reduction when compared
with Jfui'^ns ; and this culminates in the toothless JRJtyt ina. It is
also iiitere.-img to notice that in the massive lower jaw there are
traces of an incisor. "Were this to be developed into a tusk, the
jaw would present a curious resemblance to that of 2)inot7ieriuin.

The Uugong? JFf. du^itn//f lias the reputation of being the
original of the mermaid legends^ since the young is held to the
pectorally-situated breast with one flipper. ** IBufe it siioiild be
remembered," justly observes Dr. Blauford, (t that stories of
beings half man or woman, half fish, are as common in temperate
as iti tropical seas, and that some of them are more ancient than
any European knowledge of the Dugong."

Extinct Sirenians.  The earliest genus that can be with
certainty referred to this order is the Oligocene Prorastojna.
This genus, though offering no particular skull-characters that
assist in the determination of the much-debated affinities of the
Sirenia, shows a remarkable condition of the teeth that may
afford a clue. The species JP. veronense, recently described by
Mr. Lydekker,1 is founded upon a fragment of the skuH which
contains two teetli apparently representing the third and fourth
upper milk molars. The interest attaching to these teeth lies in
the fact that they clearly exhibit the buno-selenodont condition
characteristic of certain early Artiodactyles, e.g, Merycopotawwut*

JSTalitkerium is a later genus, which is known by the nearly

 Zaol* JSfoa* 1892, p. 77.
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